Radar Level Gauge Waveguide Impedance Transitions
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Solution Overview
Problem
Radar level gauge systems face inaccuracies in determining filling levels due to weak echo signals from products with similar signal propagation characteristics to the atmosphere, leading to errors in distance measurement, especially when echoes are close and interference occurs.
Innovation Solution
The use of a radar level gauge system with a waveguide probe featuring a plurality of reference impedance transitions, each with distinct reflection coefficients above and below the surface, allowing for filtering out echoes from these transitions to improve measurement accuracy by determining the position of these transitions and using a propagation velocity compensation factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radar level gauge systems use standard echo detection methods, then measurement can be performed, but measurement precision deteriorates due to weak echo signals from products with similar signal propagation characteristics to the atmosphere
Solution Approach 1:
The patent segments the echo signal analysis by identifying and separating echoes from reference impedance transitions (artificial markers on the probe) from echoes from the product surface. This segmentation allows the system to use reference echoes for calibration and compensation while focusing on surface echoes for measurement, improving precision even when product echoes are weak
Solution Approach 2:
The patent introduces reference impedance transitions as intermediary markers along the probe. These artificial reflectors serve as known reference points that enable the system to calculate propagation velocity and compensate for signal attenuation, thereby improving the reliability of detecting weak product surface echoes
2Measurement precision
If radar level gauge systems detect all reflected signals, then complete echo profile is obtained, but measurement precision deteriorates due to interference from multiple close echoes
Solution Approach 1:
The patent extracts and removes echoes from reference impedance transitions from the overall echo profile. By identifying these known reference echoes and subtracting them from the total signal, the system eliminates a major source of interference, allowing clearer detection of the product surface echo and improving measurement precision
3Measurement precision
If radar level gauge systems use reference impedance transitions, then measurement precision improves through echo filtering, but device complexity increases
Solution Approach 1:
The patent applies local quality by placing reference impedance transitions only at specific locations along the probe rather than uniformly throughout. These localized impedance changes create discrete, identifiable echo markers that provide sufficient reference information for calibration without requiring continuous modification of the probe structure, thus limiting the increase in complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy of filling level measurements by eliminating echoes from reference impedance transitions below the surface, reducing interference and improving the reliability of distance calculations, even in challenging environments like marine conditions.
Implementation Method 1
electromagnetic signals are guided towards and into the product by a probe acting as a waveguide
Implementation Method 2
each of the reference impedance transitions has a first reflection coefficient for the electromagnetic signals when the level of the surface is above the reference impedance transition and a second reflection coefficient for the electromagnetic signal when the level of the surface is below the reference impedance transition
Implementation Method 3
the distance to the surface of the product is generally determined based on the time between transmission of an electromagnetic signal and reception of the reflection thereof
Data Source
AI summary
A radar level gauge system (1) using microwaves for measuring a level of a surface (7) of a product (6) in a container (5), comprising a waveguide (3) arranged to extend into the product (6) contained in the container (5), wherein a plurality of reference impedance transitions (4a-j) are arranged at known position along the waveguide (3) and being configured to reflect a portion of transmitted electromagnetic signals back towards the transceiver (10). Preferably, each of the reference impedance transitions (4a- j) has a first reflection coefficient for the electromagnetic signals when the level of the surface (7) is above the reference impedance transition and a second reflection coefficient for the electromagnetic signal when the level of the surface (7) is below the reference reflector, the first reflection coefficient being substantially lower than the second reflection coefficient. According to this design, a higher accuracy of filling level measurements can be achieved.